Many products, such as granular and liquid materials, are shipped and stored in large bulk bags adapted to hold as much as a ton or more of material. The use of bags for this purpose has become popular recently because the bags can be shipped from the manufacturer to the material shipper in a folded and generally flat condition and, if properly designed, when empty can be returned by the user to the shipper in the same generally flat condition for reuse.
A fabric bag used in the above manner has to fulfill several practical requirements. It is of primary importance that the construction of the bag be such as to sustain relatively heavy loads. At the same time, it is essential that the bag is adapted to be folded or collapsed to a compact flat form. Frequently, because of the nature and quantity of material shipped in such bags, the bags should also be designed so that they can be easily filled and emptied of their contents. It is also desired that such bags be designed so that, when filled, they are free standing and capable of being stacked vertically one upon another. Furthermore, depending upon the type of material being shipped, some bags are also required to be moisture-proof or water resistant.
A particularly satisfactory bag is shown in U.S. Pat. No. 4,596,040.
Such bags should preferably also have some sort of attachment thereon which enables them to be lifted by the tines of a forklift truck. In the aforementioned patent, provision is made in the bag construction for receipt of the tines of a lift truck. It has also been suggested that straps be connected to the bag wherein each strap is arranged to form a loop above a corner to receive the tines of a forklift truck utilized to lift the container. However, when the load is heavy, lifting the bag by the straps, often causes tearing or separation of the connected panels of the container destroying the bag and resulting in loss of its contents.
Among the objectives of the present invention are to provide a bag having lift straps such that the bag can be easily lifted without separation of the associated connecting panels, without causing damage to or destruction of the bag, and without loss of its contents, which is adapted to be engaged with the tine of a forklift truck or other similar means for lifting the filled bag, which is rugged, durable, and is of relatively simple design and economical manufacture and assembly.
In accordance with this invention, a large bulk container is provided with a lift strap formed from a strip of flexible material. The bulk container has connecting side panels and either a closed or open top and preferably a generally rectangular shape when filled. The two ends of the strip of flexible material are secured in overlapping relationship to adjacent side panels to form a loop above the panels, and have at least one diagonal line of connection between the two sides of the strap and above the panels arranged to orient the lifting forces on the container generally into one plane and in a generally vertical direction. The lift strap thereby prevents the separation of the connected side panels and the spilling of the container contents upon lifting by the strap. Preferably, the lift strap is also fixed to the bulk container by an additional diagonal line of connection extending generally transversely to the first diagonal line which also tend to orient the lifting forces to prevent separation of the side panels.